Two of the top seven automakers boosted fleet deliveries in February and the first two months; but while one is also increasing retail sales, the other is using the higher fleet volume to offset a retail sales decline.

Nissan North America increased fleet sales 13 percent in February compared with the same month last year and also reported a 17 percent jump in retail. But at Hyundai-Kia, a 22 percent jump in fleet volume softened the impact of a 9 percent decline in February retail sales.

Nissan's U.S. sales boss, Fred Diaz, attributed some gains to business fleets buying the NV and new NV200 commercial vehicles but said that all fleet volume benefits the automaker.

"Some people are down on fleet, but it is a solid, profitable business to be in," he said.

Among the major players, retail sales inched upward 1 percent while fleet volume dropped 5 percent in a February market hampered by bad winter weather.

For General Motors, both fleet and retail lost 1 percent. Toyota Motor Sales was down 2 percent in retail sales but 18 percent on the fleet side.

Chrysler continued to cut its dependence on fleet, which dropped 13 percent while retail volume jumped 22 percent in February. For the year so far, fleet is just 23 percent of the total Chrysler sales mix compared with 29 percent a year earlier.